[GitHub] [iceberg] Reo-LEI commented on a change in pull request #2680: Core: Add RocksDBStructLikeMap

[GitBox <gi...@apache.org>]

Reo-LEI commented on a change in pull request #2680:
URL: https://github.com/apache/iceberg/pull/2680#discussion_r717620881



##########
File path: core/src/main/java/org/apache/iceberg/types/Serializers.java
##########
@@ -0,0 +1,237 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.iceberg.types;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.Map;
+import java.util.function.IntFunction;
+import org.apache.iceberg.StructLike;
+import org.apache.iceberg.data.GenericRecord;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.iceberg.util.ByteBuffers;
+
+public class Serializers {
+  private static final int NULL_MARK = -1;
+
+  private Serializers() {
+  }
+
+  public static Serializer<StructLike> forType(Types.StructType struct) {
+    return new StructLikeSerializer(struct);
+  }
+
+  public static <T> Serializer<List<T>> forType(Types.ListType list) {
+    return new ListSerializer<>(list);
+  }
+
+  public static <T> Serializer<T> forType(Type.PrimitiveType type) {
+    return new PrimitiveSerializer<>(type);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <T> Serializer<T> internal(Type type) {
+    if (type.isPrimitiveType()) {
+      return forType(type.asPrimitiveType());
+    } else if (type.isStructType()) {
+      return (Serializer<T>) forType(type.asStructType());
+    } else if (type.isListType()) {
+      return (Serializer<T>) forType(type.asListType());
+    }
+    throw new UnsupportedOperationException("Cannot determine serializer for type: " + type);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <T> Class<T> internalClass(Type type) {
+    if (type.isPrimitiveType()) {
+      return (Class<T>) type.typeId().javaClass();
+    } else if (type.isStructType()) {
+      return (Class<T>) StructLike.class;
+    } else if (type.isListType()) {
+      return (Class<T>) List.class;
+    } else if (type.isMapType()) {
+      return (Class<T>) Map.class;
+    }
+
+    throw new UnsupportedOperationException("Cannot determine expected class for type: " + type);
+  }
+
+  private static class StructLikeSerializer implements Serializer<StructLike> {
+    private final Types.StructType struct;
+    private final Serializer<Object>[] serializers;
+    private final Class<?>[] classes;
+
+    private StructLikeSerializer(Types.StructType struct) {
+      this.struct = struct;
+      this.serializers = struct.fields().stream()
+          .map(field -> internal(field.type()))
+          .toArray((IntFunction<Serializer<Object>[]>) Serializer[]::new);
+      this.classes = struct.fields().stream()
+          .map(field -> internalClass(field.type()))
+          .toArray(Class<?>[]::new);
+    }
+
+    @Override
+    public byte[] serialize(StructLike object) {
+      if (object == null) {
+        return null;
+      }
+
+      try (ByteArrayOutputStream out = new ByteArrayOutputStream();
+           DataOutputStream dos = new DataOutputStream(out)) {
+
+        for (int i = 0; i < serializers.length; i += 1) {
+          Class<?> valueClass = classes[i];
+
+          byte[] fieldData = serializers[i].serialize(object.get(i, valueClass));
+          if (fieldData == null) {
+            dos.writeInt(NULL_MARK);
+          } else {
+            dos.writeInt(fieldData.length);
+            dos.write(fieldData);
+          }
+        }
+        return out.toByteArray();
+      } catch (IOException e) {
+        throw new UncheckedIOException(e);
+      }
+    }
+
+    @Override
+    public StructLike deserialize(byte[] data) {
+      if (data == null) {
+        return null;
+      }
+
+      try (ByteArrayInputStream in = new ByteArrayInputStream(data);
+           DataInputStream dis = new DataInputStream(in)) {
+
+        GenericRecord record = GenericRecord.create(struct);
+        for (int i = 0; i < serializers.length; i += 1) {
+          int length = dis.readInt();
+
+          if (length == NULL_MARK) {
+            record.set(i, null);
+          } else {
+            byte[] fieldData = new byte[length];
+            int fieldDataSize = dis.read(fieldData);

Review comment:
       I think there should be `int fieldDataSize = length > 0 ? dis.read(fieldData) : 0;`.
   Because `dis.read()` will return -1 when fieldData lenght is 0(e.g. empty string will cause this) and make `Preconditions.checkState` fail.




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